Punchpress feed mechanism

ABSTRACT

A blank transfer fixture for a punch press including a pair of horizontal guide bars which support a manually movable carriage incorporating a blank supporting and stripping mechanism, a pusher bar for ejecting a finished blank from the press, and guide blocks for accurately positioning a blank in the press lower die. The carriage must be moved completely from a loadpress position, to a transfer-eject position, returned to the load-press position and latched in that position before a control system will allow the press to be operated.

United States Patent 1191 Dunkin 1451 Feb. 11, 1975 PUNCHPRESS FEED MECHANISM [76] Inventor: Albert Dunkin, 12 Split Rock Rd.,

South Norwalk, Conn. 06854 [22] Filed: July 13, 1973 211 Appl. No.2 379,161

[52] US. Cl 72/6, 72/421, 72/427 [51] Int. Cl B2lb 37/00 [58] Field at Search 72/25, 6, 10, 346, 427, 72/421, 419, DlG. 1.1; 113/113 R, 113 C; 83/22], 380

[56] References Cited .UNITED STATES PATENTS 2,613,720 10/1952 Baker 72/419 3,030,834 4/1962 Anderson 72/427 FOREIGN PATENTS OR APPLICATIONS 10,682 5/1907 Great Britain 72/419 Primary Examiner-C. W. Lanham Assistant Examiner-Robert M. Rogers A/mrney, Agent, or Firm-Lane, Aitken, Dunner & Ziems ABSTRACT A blank transfer fixture for a punch press including a pair of horizontal guide bars which support a manually movable carriage incorporating a blank supporting and stripping mechanism, a pusher bar for ejecting a finished blank from the press, and guide blocks for accurately positioning a blank in the press lower die. The carriage must be moved completely from a loadpress position, to a transfer-eject position, returned to the loadpress position and latched in that position before a control system will allow the press to be operated.

17 Claims, 11 Drawing Figures PATENIEUFEBI 1 n SHEET 40F 5 F/ae.

I 9 CARRIAGE IRETRACT e L I 2 R R PATEmmmi 1 ms SHEET 50F 5 llllil ,AQ

BACKGROUND OF THE INVENTION This invention relates to punch press feed mechanisms and more particularly, it concerns a novel blank transfer fixture adapted to be fitted to existing punch presses in a manner to ensure the safety of the punch press operator and to improve operation of the punch press.

Several diverse types of feed mechanisms are known to exist which purportedly enable a press operator to load a blank at a position remote from the punch press dies so that the blank may be fed to the dies without endangering the operators hands. Also many punch press operations involve automatic feeding particularly where relatively small parts are to be formed. In punch press operations where relatively large parts are to be formed, thereby involving more complicated, larger and thus more expensive dies, there has been a tendency in the industry to compromise operator safety in favor of avoiding the expense of damaging the dies or improper forming of larger and thus more expensive work pieces. The major source of die damage in presses of this type is the occurrence of more than one blank between the forming dies. Quite obviously, the presence of more than one blank can be avoided with more certainty where the operator is required to manually place the blank directly between the dies than where the blank is placed by a machine. Similarly, proper positioning of the blank between the dies to insure a quality product can be made more certain with manual operations than with various devices heretofore available. There is a practical need, therefore, for a punch press feeding fixture which, in addition to insuring ultimate operator safety, will at least insure the same measure of quality in the part formed as well as the same assurance that expensive punch dies are not damaged. Moreover, complete acceptance of such a fixture in most instances will require an enhanced rate of production and accuracy as well as economy in terms of cost of adding the fixture to an existing press.

SUMMARY OF THE PRESENT INVENTION In accordance with the present invention, a novel blank feeding fixture for punch presses is provided which is relatively simple and thus low in cost from the standpoint of both fabrication of the fixture and its installation on an existing press and which results in inherent operator safety while maintaining or improving production parameters. Structurally, the fixture employs a pair of guide bars or ways adapted to be mounted outside of the press die sets, the guide bars in turn supporting a carriage which may be advanced between a retracted load-press position at which the operator loads a blank while the press is in operation and an advanced transfer-eject station at which a part previously formed by the punch is ejected simultaneously with the transfer of a new blank to a proper position between the punch dies. A control system is provided by which the carriage must be fully latched in the loadpress position before operation of the punch press is enabled. Moreover, achievement of the latched loadpress position brings about a positive and thus accurate positioning of the new blank between the dies of the press before the press can be operated.

Among the objects of the present invention are therefore: the provision of a novel blank transfer fixture for punch press operations; the provision of such a fixture which insures operator safety and as well enhances press production and quality of formed parts; the provision of such a fixture which is simple in structure and thus low in cost and also which can be adapted to an existing press and die sets with a minimum of press modification and cost; the provision of a control system for a punch press equipped with the blank transfer fixture of the present invention by which fail-safe operation of the press is effected both from the standpoint of operator and equipment safety and the product formed; and the provision of such a blank transfer fixture of the type referred to in which the fixture components are fully integrated and cooperable with press components.

Other objects and further scope of applicability of the present invention will become apparent from the detailed description to follow taken in conjunction with the accompanying drawings in which like reference numerals designate like parts.

BRIEF DESCRIPTION OF THE DRAWINGS- FIG. 5 is an enlarged fragmentary cross-section simi-- lar to FIG. 4 but illustrating the components of the blank transfer fixture in a position corresponding to that illustrated in FIG. 2',

FIG. 6 is an enlarged fragmentary cross-section taken on line 6-6 of FIG. 3;

FIG. 7 is an enlarged fragmentary cross-section illustrating the components shown in FIG. 6 but in a different operative position;

FIG. 8 is a schematic circuit diagram of the control components of the invention;

FIG. 9 is a cross-section taken on line 99 of FIG.

FIG. 10 is an enlarged fragmentary cross-section taken on line l010 of FIG. 3; and

FIG. 11 is a cross-section taken on line 11-11 of FIG. 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawings, particularly FIGS. l-3, the blank transfer fixture of the present invention is generally designated by the reference numeral 10 and is supported on the lower frame or pedestal 12 of a punch press generally designated by the reference numeral 14. The press 14 is of conventional design and as such, includes a ram 16 movable vertically in reciprocable fashion with respect to the lower frame 12 along spaced parallel guide rods 18 and supporting on its lower surface one or more punch dies 20 depending from an upper die shoe 22. As is well known in the art, the upper punch die or dies 20 complement the shape. of and cooperate with one or more lower dies 24 supported on a die shoe 26 carried by the upper surface of the lower frame 12 to form a blank B (FIG. 4) into a finished shaped part P. For purposes of illustration it will be assumed that the blank B initially is a generally rectangular shaped piece of metal and that the finished part P assumes a dished or pan-shaped configuration essentially as shown. It will be appreciated, however, that the particular configuration of the blank or the part formed is not critical to the present invention. Also in accordance with conventional practice the lower die shoe 26 supports within the perimeter of the lower die 24 a vlier plate 28 shown only schematically in FIG. 1 for ejecting the finished part P from the lower die 24. Such plates commonly are supported by springs or other retractable means so as not to impede movement of the punch 20 downwardly into the lower die 24 but which are operable to move the plate 28 and lift it and the finished part P out of the lower die 24 to the position shown essentiallyin FIG. 1. When the finished part P is so positioned, it may be advanced horizontally to the rear of the press 14 for discharge along a chute 30.

The general organization of the blank transfer fixture of this invention as well as the components which function to receive a blank B at a loading position in front of the press (to the right of the press 14 as shown in FIGS. 1 and 2), transfer the blank to a precise position with respect to the lower die 24, and eject a finished part P onto the chute 30 at the rear of the press 14, may be understood by reference particularly to FIGS. 3-5 of the drawings. In plan, as shown in FIGS. 3, the fixture is seen to include a pair of parallel guide bars or ways 32 and 34 bolted or otherwise fixed to the top of the lower press frame I2. The guide bars are thus horizontally disposed and are located outside the press guide rods 18 so as not to interfere in any way with operative press components located between the guide rods 18. A frame-like carriage generally designated by the reference numeral 36 and including a pair of longitudinal side bars 38 and 40 is supported for reciprocable fore and aft movement on the guide bars 32 and 34 by four roller brackets 42, 44, 46 and 48. As shown in FIG. 3, the roller brackets are connected in cantilevered fashion to the side bars 38 and 40 so that these members may be spaced inwardly of the guide bars 32 and 34 and also inwardly of the die set rods 18. At the forward end of the side bars 38 and 40 are a pair of upstanding handles 50 by which the carriage 36 may be moved between a retracted load-press position illustrated in FIGS. 1 and 3 and an advanced transfer-eject position illustrated in FIG. 2. A blank receiving and transfer mechanism generally designated by the reference numeral 52 is supported from the carriage 36 and the mechanism 52 in turn includes front and rear blank supporting and stripping assemblies 54 and 56 extending transversely of the carriage between the side bars 38 and 40 thereof.

The assemblies 54 and 56, as shown most clearly in FIGS. 4 and of the drawings, include components which are either connected directly to and thus fixed to the side bars 38 and 40 by screws 58 and 60 or which are permitted a measure of movement relative to the side bars 38 in the manner to be described. Thus, the rear blank support and stripping assembly 56 is constructed to include a blank shelf 62 formed as a plate extending between the carriage side bars 38 and 40 fixed by suitable means such as rivets 65 to an upper plate 66 spaced vertically from the shelf 62 and overlying an intermediate mounting plate 68 connected directly to the carriage side bars 38 and 40 by the screws 60. A rear stripper bar 70 extends transversely between the carriage side bars 38 and 40 but is slidably supported between the plates 62 and 66 for movement with respect to these plates and the side bars 38 and 40. The opposite ends of the rear stripper bar is connected by rivets or bolts 72 to a pair of control bars 74 extending longitudinally of the carriage and throughout the length of the blank receiving and transfer mechanism 52. The control bars 74 are connected near their forward end by screw bolts 76 or other suitable means directly to a front blank supporting shelf or plate 78, a spacer bar 80, and an upper plate 82, all of which extend between but are not connected to the carriage side bars 38 and 40. Situated between the plates 78 and 80 in vertical supporting fashion is a front stripper bar 84 extending between and connected directly to the carriage side bars 38 and 40 by the screws 58. In light of this organization, it will be appreciated that the rear shelf 62 and the front stripper bar 84 will move directly with the carriage side bars 38 and 40 whereas the rear stripper bar 70 and the front blank supporting shelf'78 will float or slide relative to the carriage along with the control bars 74.

Movement of the control bars 74 and components connected to it for movement relative to the side bars 38 and 49 of the carriage is controlled by stop lugs 86 fixed such as by bolts 88 at the front of the lower press die shoe 26, as shown in FIGS. 4 and 5. The control bar 74 carries a rear stop block 90 adapted to engage the lugs 86 during movement of the carriage to its retracted or load-press position (FIGS. 1, 3 and 4) and a front stop block 92 adapted to engage the stop lugs 86 during advancement to the transfer-eject position (FIGS. 2 and 5). Thus when the carriage 52 is fully retracted, the stop block 90, in abutting the lugs 86 on the press, will hold the rear stripper bar 70 as well as the front blank shelf 78 in the position shown in FIG. 4 and in a condition to receive a new blank B. When the carriage is advanced manually into the press, the front stop block 92 on the control bars 74 will engage the stop lugs 86 to interrupt movement of the front blank shelf 78 and the rear stripper block 70. With a slight measure of attendent further movement of the carriage, the rear blank supporting shelf 62 and the front stripper block 84, because of their direct connection to the side bars 38 and 40, will move to the relative position shown in FIG. 5 so that the blank B will drop downwardly into position over the lower die 24.

To ensure accurate positioning of the blank B with respect to the lower die 24, one or more blank positioning blocks 94 having a camphered front edge 96 are welded, bolted or otherwise secured to the forwardmost portion of the lower die 24 and generally positioned above the die 24. The guide blocks 94 will cause the blank to drop downwardly and to the rear thereof. To ensure that the blank is positioned firmly against the guide blocks 94, rear guide blocks 98 (FIGS. 1 and 3) are supported on the underside of a rear stop bar 99 extending between the carriage side bars 38 and 40. Thus, when the carriage is retracted to its blank receiving or loading position, the rear guide blocks 98 engage the rear edge of the blank B to position it firmly against the front guide blocks 94. In this way, accurate positioning of the blank B is achieved.

It will be noted in FIG. 3 that the front and rear blank supporting shelves 78 and 62, respectively, may carry L-shaped blank positioning devices 100 in the event multiple blanks are to be advanced simultaneously to the press. In this instance, the stripper bars 70 and 84 are provided with projecting stripper blocks 102 so that the relative movement between the stripper bars and the supporting shelves described above may effect transfer of the blank from the carriage to the position shown in FIG. 5 over the lower die 24.

The carriage also supports between the rear stop bar 99 and the blank receiving and transfer mechanism 52, a finished part ejection or pusher bar 104 extending between and fixed to the side bars 38 and 40. As shown in FIGS. l3, the pusher bar 104 projects downwardly under the carriage by a sufficient amount so that it will engage the formed part P after it has been elevated by the vlier plate 28 to move the part P rearwardly onto the discharge chute 30.

Although the blank transfer fixture of the present invention includes additional and important control components to be described in more detail below, the basic cycle of operation of the parts described above to load and punch a blank as well as to eject a completed part may now be understood. With the upper punch die 20 in the retracted position, as shown in FIGS. 1 and 2 of the drawings, and the carriage 36 retracted to its forward-most position as shown in FIGS. 1 and 3, the operator of the press places a blank B onto the shelves 62 and 78 of the blank receiving and transfer mechanism 52. He then advances the carriage toward the press 14 until no further movement is possible as a result of means to be described in more detail below, such that near the end of this forward movement the blank B is transferred onto the lower die 24. The carriage 36 is then retracted so that the rear guide blocks 98 move the blank B firmly into position against the front guide blocks 94 as described above with respect to FIGS. 1, 3 and 5. The press is now operated so that the punch 20 advances downwardly against the blank B to form the finished part and is retracted, the part P being elevated by the vlier plate 28 to a position above the level of the lower die 24. After having loaded a new blank or blanks to be positioned in the press, the operator again advances the carriage so that the pusher bar 104 will eject the previously finished part P onto the chute 30 and the new blanks transferred to the lower die 24 in the manner described above. Because of this basic cycle of operation, the operators hands need approach the press only to the extent that he must grasp the handles 50 to advance the carriage. Although this factor, in itself, involves an inherent measure of safety, a shield 106 depicted by phantom lines in FIGS. 1 and 2 may be mounted on the press to preclude the operators hand physically from advancing between the upper and lower press dies 20 and 24.

Although the added measure of safety to the operator of the press 14 equipped with the fixture is apparent by comparison to previous techniques involving the loading of the blanks B directly onto the lower press die 24, industry acceptance of the fixture and its inherent safety features necessitates the avoidance of various production deterrents such as inaccuracy of blank placement on the lower die 24 to assure accuracy in the formed part P and the avoidance of double blanks being positioned between the dies and 24 during operation of the press which may result in costly damage to the dies. To these ends, the blank transfer fixture 10 is equipped with means both for preventing movement of the carriage 36 during descending operative movement of the punch 20 and to prevent operation of the press unless and until the carriage 36 as well as the blank B and finished part P are fully and properly positioned to enable press operation. As shown in FIGS. 3, 6, 7 and 9 of the drawings, the rear roller brackets 46 support a depending latch plate 106 having a camphered forward lower edge 108. The plate depends from the bracket 46 sufficiently to cooperate with a latch assembly 110 supported by a mounting bracket 112 secured by appropriate means (not shown) to'the inside face of the guide bar 32. The latch 110 includes a bar member 114 pivotally supported by a stud 116 projecting from the mounting bracket 112 and a catch 118 pivotally supported from a forward bifurcated end of the bar 114 by a pin 120. The latch 110 is biased so that the forward end of the bar 114 and the catch 118 are urged upwardly toward the latch plate 106 and the upper press ram 16 by a helical compression spring 122 extending between the bar 114 and a ledge 124 on the mounting bracket 112. Similarly, the catch 118 is biased to a latch blocking position shown in FIG. 6 by a compression spring 126 extending between the forward end of the bar 114 and a recess 128 in the catch positioned below the pivotal pin 120. The catch 118 is provided with an inclined upper top surface 130 which joins with a catch abutment surface 132, these surfaces being in a position relative to the plate 106 so that the plate 106 will not be engaged by the catch 118 when the plate is positioned as shown in FIG. 6 or as the plate is advanced with the carriage when the latter is moved in the direction of the advanced transfer-eject position. Because of the direction of bias in the springs 122 and 126 as well as the relative location of the latch 110 to the latch plate 106, however, the plate 106 and thus the carriage to which it is rigidly fixed will be engaged by the latch as the cariage is retracted back against the surface 132 on the catch 110. It will, moreover, be positively held in this position by virtue of the relative posi-- tions of the latch plate 106 and the latch bar 114 as shown in FIG. 7 of the drawings.

In addition, and as shown most clearly in FIGS. 6, 7 and 9, the mounting bracket 112 is formed with a forwardly projecting downwardly facing abutment surface 133. The width and location of the catch 118 (FIG. -9) is such that one side of the top surface 130 of the catch underlies the surface 133 when the catch 118 is in the position shown in FIG. 6, the latch bar 114 will be retained essentially in the position shown in FIG. 6, irrespective of the presence of the plate 106 or other press components to be described.

The basic cycle of operation explained above, in light of the organization of the latch 110 will permit advancing movement of the carriage 36 to drop the blank B on the lower die 24, to eject the previously finished part P and retracting movement of the carriage so that the rear guide blocks 98 position the new blank positively against the front surfaces of the front guide blocks 94 (FIG. 5). Simultaneously with this latter action, the latch plate 106 will engage the abutment surface 132 on the catch 118 to latch the carriage firmly in its retracted position. Accordingly, the punch ram 16 may now be lowered to force the punch die 20 downwardly against the blank and the lower die 24.

To effect release of the catch 118 from the latch plate 106, the press ram 16 is provided on its rear face with an adjustable plunger 134 (see FIGS. 1, 2, 6 and 7) positioned to engage the forward end of the latch bar 114 and to press it against the bias of the spring 122 out of engagement with the latch plate 106. To prevent the latch from reengaging when the ram moves upwardly returning to its initial position, the spring 126 moves the catch 118 to the position shown in FIG. 6 in which the top surface 130 of the catch 118 abuts the lower end of the latch plate 106 or the abutment surface 133 on the bracket 112. Hence, the latch plate 106 and thus the carriage is freed for movement again to the transfer-eject position.

Reference is now made to FIGS. 3 and 6-8 of the drawings, in which is shown the structural organization of components and electric circuitry by which operation of the punch 14 is controlled in response to movement and positioning of the carriage 36. As shown in FIGS. 3, 6 and 7, supported on the guide bar 32 in addition to the latch 110 is a limit switch LS2 having an actuator 136 in engagement with the bottom of the latch bar 114 at the rear end thereof, and a further limit switch LS-l positioned to be engaged by the forward face of the latch 106 when the carriage is advanced fully to its transfer eject position. Thus it will be appreciated that the condition of the limit switch LS-2 will be changed with the pivotal movement of the latch bar 114 between the positions illustrated respectively in FIGS. 6 and 7 and that the condition of the limit switch LS-l will be changed upon engagement thereof by the latch plate 106. The manner in which the change in states of the limits switches LS-l and LS-2 effect operation of the press may be understood by reference to the circuit diagram shown in FIG. 8. Conventional control for operation of the press 14 includes a control unit C in a power circuit with a pushbutton switch S. In accordance with the invention, an additional relay control circuit is provided across terminals T-l and T-2. The electrical position of the limit switches in the control circuit is apparent from the reference character designations shown. In addition to the limit switches, two relays R-1 and R-2 are included, the relay R-1 controlling the condition of two normally opened relay switches RS-la and RS-lb. The relay R-2, on the other hand, controls the condition of two normally opened relay switches RS-2a and RS-2c and in addition controls normally closed relay switch RS-Zb.

In the context of press operation, the limit switch LS-2 will be open when the latch bar 114 is retained in the position of FIG. 6 by any one of the plunger 134, the latch bar 106 or the abutment surface 133 and therefor closed only when the latch plate is latched in the position shown in FIG. 7. Thus, at the beginning of a press cycle of operation, the switch LS-2 will be open and the remaining switches in the position shown in FIG. 8 to disable the press control circuit. When the carriage is advanced toward and reaches the end of its advancing travel and closes the limit switch LS-l, a circuit is completed through LS-l, RS-2b and the relay coil R-l. Energization of the coil R-l, in turn, closes the switch RS-la and the switch RS-lb. Thus the energized condition of the relay coil R-l will remain after the carriage is retracted to open the switch LS-l. Then, when the latch 110 engages the latch plate 106 to hold the carriage in its load-press position, the limit switch LS-2 will be closed to energize the relay coil R-2 initially through the switch RS-lb, and LS-2. Energization of the relay coil R-2 in turn will open the normally closed relay switch RS-Zb to open the holding circuit through relay coil R-l, close switch RS-2c to complete a circuit through RS-Zc, LS-2 and R-2, and close switch RS-Za in the press control circuit. Thus, at this time the main control switch S may be closed to actuate the press. When the press ram 16 moves downwardly and the adjustment plunger 134 disengages the latch bar 114 as described above, latch and limit switch LS-2 will be actuated to open the holding circuit through relay coil R-2.

In light of the control circuitry and its organization with the latch 110, it will be appreciated that the carriage must first be moved completely to its transfereject position and returned to its load-press position before operation of the press is permitted. Because of this control arrangement, the finished part P must be fully ejected from the press and the carriage must be returned to the load-press position with the new blank firmly against the guide block 94 before the press can be actuated thereby to assure not only that the opera tors hands are in a remote position from the press but also to insure full ejection of the previously finished part and positive complete location of the newly fed blank B.

As shown in FIGS. 9 and 10 of the drawings, the roller bracket 48 by which the carriage is supported in part from the guide bar 34 on the opposite side of the press from the limit switches described above, may include a hydraulic or pneumatic cushioning arrangement as shown in these figures. Specifically, a pair of shock absorbers 136 and 138 may be supported from the roller bracket 48 to engage, respectively, a stop block 140 at the rear end of the guide bar 34 and a stop block (not shown) positioned at the rear edge of the press 14. Because of this arrangement, final movement of the carriage to its respective terminal positions may be cushioned in advance of metal to metal impact of the movement terminating abutment surfaces previously described. This feature is important to relatively large press installations where the mass of the carriage is great.

Thus it will be appreciated that by this invention, there is provided a highly effective blank transfer and handling fixture for punch presses by which the above mentioned objectives are completely fulfilled. It also will be appreciated that various modifications and/or changes can be made in the embodiment described without departure from the spirit or scope of the present invention. It is expressly intended, therefore, that the foregoing description is illustrative only of a preferred embodiment, not limiting, and that the true spirit and scope of the present invention will be determined by reference to the appended claims.

I claim: I

l. A blank feeding fixture for punch presses of the type having a pair of relatively movable dies cooperable to form a part upon movement against a blank positioned between the dies, said fixture comprising:

blank carriage means movable between a retracted loading position remote from the press dies and an advanced transfer position at which a blank supported by said carriage means is placed between the press dies;

retractable latch means engageable with said carriage means upon movement thereof to said retracted loading position and for retaining said carriage means in said retracted position;

means for releasing said latch means from retaining engagement with said carriage means upon terminal movement of the press dies against a blank; and

control means for enabling relative movement of the press dies against the blank only when said latch means is operative to retain said carriage means in said retracted loading position.

2. The apparatus recited in claim 1 wherein said carriage means includes:

shelf means to support the blank during movement from said retracted position to said advanced position; and

means for stripping the blank from said shelf means upon movement of said carriage to said advanced position thereby to effect a transfer of the blank from said shelf means to a position between press dies automatically in response to carriage movement to said advanced position.

3. A blank feeding fixture for punch presses of the type having a pair of relatively movable dies cooperable to form a part upon movement against a blank positioned between the dies, said fixture comprising:

blank carriage means movable between a retracted loading position remote from the press dies and an advanced transfer position at which a blank supported by said carriage means is placed between the press dies;

latch means for retaining said carriage means in said retracted position;

control means for enabling relative movement of the press dies against the blank only when said latch means is operative to retain said carriage means in said retracted loading position;

said carriage means including a first shelf fixed to said carriage means and adapted to support the blank under one edge thereof;

a second shelf spaced from said first shelf to engage the blank under an opposite edge thereof, said second shelf being supported for movement on said carriage relatively to said first shelf;

first stripper means supported by said carriage for movement relative to said first shelf;

second stripper means fixed to said carriage means in operative relation to said second shelf means; and

means connecting said first stripper means and said second shelf means whereby relative movement between said carriage and said last-mentioned means will effect transfer of the blank from the carriage to the fixed press die.

4. The apparatus recited in claim 3 including stop means adapted to be mounted on the press at a position correlated to the location of the press dies and to the location of the blank transfer from said carriage, and wherein said last-mentioned means carries spaced abutments to engage said stop means during terminal movement of said carriage to effect relative movement between said second shelf and said first stripper means on the one hand and said first shelf means and said second stripper means on the other hand to position said shelf means and said stripper means relative to each other to receive said blank when said carriage is at said retracted position and to transfer said blank to a position between the press dies when the carriage is moved to its advanced position.

5. The apparatus recited in claim 4 wherein said carriage includes a pair of spaced parallel side bars and wherein said last-mentioned means comprises a pair of control bars underlying said side bars, said abutments being carried by said control bars.

6. The apparatus recited in claim 5 wherein said second shelf is supported by said second stripper means i and whereby first stripper means is supported by said first shelf.

7. A blank feeding fixture for punch presses of the type having a pair of relatively movable dies cooperable to form a part upon movement against a blank positioned between the dies, said fixture comprising:

blank carriage means movable between a retracted leading position remote from the press dies and an advanced transfer placed between the press dies;

latch means for retaining said carriage means in said retracted position;

control means for enabling relative movement of the press dies against the blank only when said latch means is operative to retain said carriage means in said retracted loading position, said latch means comprising a latch plate fixed to said carriage;

a movable catch to engage said latch plate and mountable in fixed positional relation to one of the press dies; I

' means biasing said catch toward the other of said press dies and said latch plate; and means to block engagement of said latch plate by said catch except when said carriageis moved in the direction of said retracted loading position. i

8. The apparatus recited in claim 7 including a latch bar pivotally supporting said catch, said latch plate being engagable between said catch and said latch bar, and means biasing said catch toward said latch bar to prevent engagement of said latch plate except when said carriage and thus said latch plate is moved in a direction to pivot said catch in said bias to prevent entry of said latch plate between said catch and said latch bar.

9. The apparatus recited in claim 1 including means on said carriage for ejecting a formed part from said press during movement of said carriage from said retracted loading position to said advanced transfer position.

10. The apparatus recited in claim 1 including handle means on said carriage for manual advance of said carriage between said positions thereby to insure operator safety by requiring the operators hands to be positioned remotely from the press dies during operation.

11. In a punch press having a'fixed lower frame supporting an upwardly facing lower die and a vertically reciprocable ram supporting a downwardly facing upper die cooperable with the lower die to form a part from a blank positioned on the lower die after advancement of the upper die downwardly against the blank and the fixed die, a blank feeding fixture comprising:

a pair of parallel guide ways mounted on said lower frame on opposite sides of the lower die;

blankcarriage means supported on said guide ways for movement horizontally between a retracted loading position displaced from the lower press die and an advanced transfer position at which a blank supported by said carriage means is positioned over said lower die;

latch means supported by said guide ways and engageable with said carriage means upon movement thereof to said retracted loading position and for locking said carriage in said retracted loading position; and

control means for enabling downward movement of the upper press die against the blank and the lower die only when said latch means is operative to lock said carriage means in said retracted loading position.

12. The apparatus recited in claim 11 including means on said carriage for automatically dropping a blank over the lower press die and including further blank guide block means in precise fixed relation to the lower press die to be engaged by and thus locate one edge of the blank and stop bar means carried by said carriage to engage the opposite edge of said blank and to retain the blank against said guide block means upon movement of said carriage to said retracted loading position.

13. The apparatus recited in claim 7 including means on said carriage for ejecting a formed part from a position on the lower press die during movement of said carriage to said advanced transfer position.

14. The apparatus recited in claim 13 wherein said control means comprises means for sensing the location of said carriage in said advanced transfer position; means for sensing the latching of said carriage by said latch means; a control circuit for actuating the upper press ram thereby to advance it against the blank and the lower die; and means responsive to movement of the carriage from said retracted position to said advanced position and back to said retracted position for enabling said press actuating control means.

15. The apparatus recited in claim 11 in which said carriage is supported on said guide ways by cantilevered roller blocks thereby to enable said guide ways to be mounted remotely of press operating components.

16. The apparatus recited in claim 15 including cushioning means for absorbing the impact of carriage movement between said positions.

17. The apparatus recited in claim 11 including means carried by the press ram for disengaging said latch. means upon operation of the press to form a part. 

1. A blank feeding fixture for punch presses of the type having a pair of relatively movable dies cooperable to form a part upon movement against a blank positioned between the dies, said fixture comprising: blank carriage means movable between a retracted loading position remote from the press dies and an advanced transfer position at which a blank supported by said carriage means is placed between the press dies; retractable latch means engageable with said carriage means upon movement thereof to said retracted loading position and for retaining said carriage means in said retracted position; means for releasing said latch means from retaining engagement with said carriage means upon terminal movement of the press dies against a blank; and control means for enabling relative movement of the press dies against the blank only when said latch means is operative to retain said carriage means in said retracted loading position.
 2. The apparatus recited in claim 1 wherein said carriage means includes: shelf means to support the blank during movement from said retracted position to said advanced position; and means for stripping the blank from said shelf means upon movement of said carriage to said advanced position thereby to effect a transfer of the blank from said shelf means to a position between press dies automatically in response to carriage movement to said advanced position.
 3. A blank feeding fixture for punch presses of the type having a pair of relatively movable dies cooperable to form a part upon movement against a blank positioned between the dies, said fixture comprising: blank carriage means movable between a retracted loading position remote from the press dies and an advanced transfer position at which a blank supported by said carriage means is placed between the press dies; latch means for retaining said carriage means in said retracted position; control means for enabling relative movement of the press dies against the blank only when said latch means is operative to retain said carriage means in said retracted loading position; said carriage means including a first shelf fixed to said carriage means and adapted to support the blank under one edge thereof; a second shelf spaced from said first shelf to engage the blank under an opposite edge thereof, said second shelf being supported for movement on said carriage relatively to said first shelf; first stripper means supported by said carriage for movement relative to said first shelf; second stripper means fixed to said carriage means in operative relation to said second shelf means; and means connecting said first stripper means and said second shelf means whereby relative movement between said carriage and said last-mentioned means will effect transfer of the blank from the carriage to the fixed press die.
 4. The apparatus recited in claim 3 including stop means adapted to be mounted on the press at a position correlated to the location of the press dies and to the location of the blank transfer from said carriage, and wherein said last-mentioned means carries spaced abutments to engage said stop means during terminal movement of said carriage to effect relative movement between said second shelf and said first stripper means on the one hand and said first shelf means and said second stripper means on the other hand to position said shelf means and said stripper means relative to each other to receive said blank when said carriage is at said retracted position and to transfer said blank to a position between the press dies when the carriage is moved to its advanced position.
 5. The apparatus recited in claim 4 wherein said carriage includes a pair of spaced parallel side bars and wherein said last-mentioned means comprises a pair of control bars underlying said side bars, said abutments Being carried by said control bars.
 6. The apparatus recited in claim 5 wherein said second shelf is supported by said second stripper means and whereby first stripper means is supported by said first shelf.
 7. A blank feeding fixture for punch presses of the type having a pair of relatively movable dies cooperable to form a part upon movement against a blank positioned between the dies, said fixture comprising: blank carriage means movable between a retracted leading position remote from the press dies and an advanced transfer placed between the press dies; latch means for retaining said carriage means in said retracted position; control means for enabling relative movement of the press dies against the blank only when said latch means is operative to retain said carriage means in said retracted loading position, said latch means comprising a latch plate fixed to said carriage; a movable catch to engage said latch plate and mountable in fixed positional relation to one of the press dies; means biasing said catch toward the other of said press dies and said latch plate; and means to block engagement of said latch plate by said catch except when said carriage is moved in the direction of said retracted loading position.
 8. The apparatus recited in claim 7 including a latch bar pivotally supporting said catch, said latch plate being engagable between said catch and said latch bar, and means biasing said catch toward said latch bar to prevent engagement of said latch plate except when said carriage and thus said latch plate is moved in a direction to pivot said catch in said bias to prevent entry of said latch plate between said catch and said latch bar.
 9. The apparatus recited in claim 1 including means on said carriage for ejecting a formed part from said press during movement of said carriage from said retracted loading position to said advanced transfer position.
 10. The apparatus recited in claim 1 including handle means on said carriage for manual advance of said carriage between said positions thereby to insure operator safety by requiring the operator''s hands to be positioned remotely from the press dies during operation.
 11. In a punch press having a fixed lower frame supporting an upwardly facing lower die and a vertically reciprocable ram supporting a downwardly facing upper die cooperable with the lower die to form a part from a blank positioned on the lower die after advancement of the upper die downwardly against the blank and the fixed die, a blank feeding fixture comprising: a pair of parallel guide ways mounted on said lower frame on opposite sides of the lower die; blank carriage means supported on said guide ways for movement horizontally between a retracted loading position displaced from the lower press die and an advanced transfer position at which a blank supported by said carriage means is positioned over said lower die; latch means supported by said guide ways and engageable with said carriage means upon movement thereof to said retracted loading position and for locking said carriage in said retracted loading position; and control means for enabling downward movement of the upper press die against the blank and the lower die only when said latch means is operative to lock said carriage means in said retracted loading position.
 12. The apparatus recited in claim 11 including means on said carriage for automatically dropping a blank over the lower press die and including further blank guide block means in precise fixed relation to the lower press die to be engaged by and thus locate one edge of the blank and stop bar means carried by said carriage to engage the opposite edge of said blank and to retain the blank against said guide block means upon movement of said carriage to said retracted loading position.
 13. The apparatus recited in claim 7 including means on said carriage for ejecting a formed part from a position on the lower press die during movement of said carriage to said advAnced transfer position.
 14. The apparatus recited in claim 13 wherein said control means comprises means for sensing the location of said carriage in said advanced transfer position; means for sensing the latching of said carriage by said latch means; a control circuit for actuating the upper press ram thereby to advance it against the blank and the lower die; and means responsive to movement of the carriage from said retracted position to said advanced position and back to said retracted position for enabling said press actuating control means.
 15. The apparatus recited in claim 11 in which said carriage is supported on said guide ways by cantilevered roller blocks thereby to enable said guide ways to be mounted remotely of press operating components.
 16. The apparatus recited in claim 15 including cushioning means for absorbing the impact of carriage movement between said positions.
 17. The apparatus recited in claim 11 including means carried by the press ram for disengaging said latch means upon operation of the press to form a part. 